Many communications networks incorporate techniques for encryption of the information transmitted between components in the network. For example, a local area network (LAN) connecting multiple end stations and supporting Internet Protocol (IP) might incorporate a technique for encrypting voice, data, video, or other information streams transmitted between end stations during a communications session. Successful operation of the network will in many instances depend on the ability of this encryption technique to satisfy performance, flexibility, regulatory, and other requirements while providing a desired level of privacy for communications over the network.
As the communications industry continues to dominate the growth of the global economy, providing a desired level of privacy for network users while also satisfying performance, flexibility, regulatory, and other requirements has become increasingly important. In particular, the advent of IP telephony has increased the requirements for information privacy to a marked degree. However, prior encryption techniques used for transferring information streams between computers typically involve computationally intensive encipherment techniques that provide a much higher level of security than is typically needed for IP telephony. As such, use of these techniques in an IP telephony environment may contravene the cryptography axiom that the encryptor should ideally be tailored to particular security needs rather than providing, in all situations and without regard to the data being transmitted, the most powerful encryption possible. Other prior encryption techniques, although generally better adapted to the information and other requirements associated with IP telephony, use relatively simple linear and non-linear feedback shift registers to provide the output key sequences. Although such techniques provide reasonable levels of security and are typically less computationally intensive, they are often inflexible in their structure and with respect to the privacy provided. As a result of these and other deficiencies, prior encryption techniques are inadequate to meet the requirements associated with IP telephony and other communications within communications networks.